1. Field of the Invention
This invention relates to a stereo eye fundus camera or an eye fundus camera for illuminating the fundus of an eye to be tested through an objective lens and guiding a reflected beam of light from the eye fundus to a stereo type image formation optical system in order to stereoscopically observe the eye fundus.
2. Description of the Prior Art
Heretofore, a stereo type eye fundus camera has an illumination optical system for illuninating the eye fundus through an objective lens. The illumination light is reflected by the eye fundus. A reflected beam of light from the eye fundus is split by a two-aperture diaphragm. The reflected beam which was split by the two-aperture diaphragm, is guided to a stereo type image formation optical system. And a man can stereoscopically observe the eye fundus by the stereo type image formation optical system.
Also, such split reflected beams are simultaneously separately imaged on respective portions of a sheet of film by the stereo type image formation optical system. By this, a pair of eye fundus images having a parallax are taken on a sheet of photograph.
Analysis of a three-dimensional configuration of the eye fundus is performed by comparing the pair of eye fundus images taken on the sheet of photograph. That is, various component parts of one fundus image are compared with the corresponding component parts of the other eye fundus image. And parallax is measured for each component part. By this, the three-dimensional configuration of the eye fundus is analyzed.
However, there are parts having uniform reflection factors in the eye fundus. There is also a part, like a papilla, having a high reflection factor in the eye fundus.
In such a case like this, when the eye fundus is taken using the conventional stereo type eye fundus camera, the eye fundus is taken as a plane image having a vague border even if there are irregularities on the eye fundus because the portion having uniform reflection factors is low in contrast. Therefore, it is difficult to compare the various component parts of a portion having the uniform reflection factors of one eye fundus image with the corresponding component parts of a portion having the uniform reflection factors of the other eye fundus image, and it is very difficult to three-dimensionally analyze the configuration of the eye fundus.
On the other hand, the papilla portion has a high reflection factor. Therefore, when the papilla is taken, it becomes overexposure. As a consequence, the analysis of the three-dimensional configuration of the papilla portion is difficult.